1. FIELD OF THE INVENTION
This invention relates to a driving circuit for brushless DC motor furnished with an angular position detecting element.
2. DESCRIPTION OF THE PRIOR ART
Hitherto, there is known a driving circuit for a motor, in which the angular positions of the rotor of the motor are detected by means of a contactless detector so as to control the currents through the corresponding coils of the armature winding in response to the output of the detector.
With the conventional driving circuit of this kind, the corresponding coils of the stator winding are energized with the signal obtained by converting the output of the angular position detecting elements provided along the stator into a signal having a constant pulse width suitable for motor-driving by the use of a pulse-forming circuit including a level shifting circuit comprising zener diodes.
However, such a conventional driving circuit requires many circuit elements such as zener diodes and resistors so that the overall circuit becomes complicated and also consumes a considerable power. This gives rise to a drawback that the integration of the driving circuit is very difficult. Further, the conventional driving circuit is liable to be affected by the fluctuation of the ambient temperature so that it cannot be free from a drawback that the rotational speed adversely fluctuates.